The present invention relates to a composition for dyeing keratin fibers which contains o-benzoquinone in combination with certain amino or hydroxy compound, as well as a method for dyeing keratin fibers using this composition.
Generally direct-dyeing dye compounds or oxidation dyestuffs which arise by oxidative coupling of one or more developer substances together with one or more coupler substances are used for dyeing of keratin-containing fibers, for example hair, wool or fur. Intense dyeing with good fastness properties may of course be obtained with oxidation dyestuffs which develop the color, however strong oxidizing agents, such as hydrogen peroxide, which are used frequently cause damage to the fibers. Direct-dyeing hair dyes are applied under safer conditions, but have the disadvantage that they have unsatisfactory fastness properties.
According to German Patent Application DE-OS 43 35 624 dye compositions based on p-benzoquinone, which avoid the use of an additional oxidizing agent, provide an alternative here.
The dyeing process described in German Patent Application DE-OS 43 35 624 is however difficult to perform in practice, since the dye mixture must be heated prior to use to its boiling temperature and subsequently filtered and frequently leads to unsatisfactory dyeing results.